If you guys crash after leaving port it maybe something wrong with ports. I had same problem what I did i just moved the harbour spawn points abit further and worked.
from SH 5 Wolfes of steel I think its the same for SH 3
Save and restart your game completely once you leave your home base or when approaching for docking (100-200 km from the home base approx.) This will improve game stability and unburden game engine for upcoming rendering "shocks". It is always good idea to make a manual gamesave in the bunker and restart the game before you start new patrol. Don't delete your bunker saves, you may need them again.
So if you don't want to restart the game after leaving port just change in mission editor where to spawn I hope that helps if you have any questions feel free to ask
Sorry for bad English